What is Availability? The definition of availability of a generator will vary depending on the application of the generator. The availability of the generator is an indicator of reliability.
For example, the generator may be a unit in a multi-unit, prime power station. The availability of the generator may be considered as the number of hours each year that the generator is available either as a fixed reserve or that the generator is in service, expressed as a percentage. The availability of each generation unit may be different and also different to the availability of the prime power station.
As another example, the generator may be operating as a distributed generator with a feed-in tariff from the utility. The availability of the generator may be considered as the number of hours each year that the generator is connected to the grid and operating at rated power output, expressed as a percentage.
What is the Economic Value of Availability? In order to evaluate investment options, it can be helpful to put an economic value on availability. The economic value may vary depending on the specific application and the costs for the user. The benefit of determining an economic value is that it can be used in accounting models such as return-on-investment and net-present-value. This provides information for management which can be used to determine how to direct investment.
This can be illustrated if the example of the distributed generator is considered. Let’s assume the generator runs with an availability of 90%. This means that during the year, the generator is not online for 876 hours. Let’s also assume the generator capacity is 2 MW and the feed-in tariff is 50 cents per kWHr. The remaining life of the installation is estimated to be three years.
The loss of revenue during one year can be calculated by multiplying the feed-in tariff by the number of kWHr lost during the year. The problem is to minimise the lost income and to increase revenue.
What if there was a control solution for improving the availability to 97%, but the cost of implementation was $ 100,000? How do you know if this would be a viable investment?
In this example, if the availability is increased from 90% to 97%, the number of additional hours online each year is 613.2 hours. The number of kWHr is 1,226,400 per year. At a feed-in tariff of 50 cents, the extra income each year is $ 613,200. Over the remaining life of the generator, the total income is $ 1,839,600, for an investment cost of $ 100,000. Clearly, without further accounting analysis, this would be a good investment.
Not all solutions are so clear cut. In many instances there are subjective elements to be estimated. The role of applying an economic evaluation is to identify the economic benefit or otherwise of the proposal.
Solutions for Improving Availability through Power and Control Systems BESST Engineering is able to identify opportunities, evaluate options and provide solutions for improving the availability generators through power and control systems, whether it is a new power station design application or an existing installation.